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Sixuan Chen

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Posts posted by Sixuan Chen


  1. Hi Hyperman,

     

    Thank you for the response, I looked into it and posted my response. Please check it out.

     

    Best,

    Peter

    2 hours ago, Hyperman said:

    In the model you shared the optimization problem was actually min volume fraction with a constrained frequency of the first mode. The objective and constraint should be switched as you proposed (min 1st frequency s.t. 0.5 VF).

     

    To make sense of topology optimization results it is useful to output ESE- strain energy. 

    1.jpg

    2.jpg

    3.jpg

    I have reduced the order of tetra elements and meshed the design space with hexahedral elements to save computation time. Note however the model is stiffer due to 1st order tetra- the plate should be structured hexahedral meshed for accuracy and efficiency. The minimum and maximum member size were used on topology>parameters. Door_opt_Topo_Opt-edit1.hm

    4.jpg

    Refer to a similar example OS-E: 3005 Eigenvalue Maximization for alternative approaches (topography + multi frequency optimization setup).

    OS-E_ 3005 Eigenvalue Maximization.pdf 229.11 kB · 1 download eigenplate.fem 590.28 kB · 0 downloads

     

     


  2. Thank you for the detailed answer.

     

    The reason I set up constraint on frequency is because we want optimized model have natural frequency more than 200Hz.

     

    For the example you provided, it uses topography configuration instead of topology. I have tried this approach and obtained some reasonable results.

    The topography approach will give me design that drawn beads on the plate, however, we also want to see possible solution that attach/weld additional components on the plate.

     

    Also I can't open the edited model you attached because of the version (mine is 2017). I made a model in creo based on the last image you attached (optimization result), the modal analysis give a natural frequency of 42Hz, which is far from enough. Could you please help to solve this issue?  

     

    Thanks!

     

    image.png

    image.png

    image.png


  3. Dear all,

     

    I'm working on a project as the attached image shown: We want to increase the natural frequency of the blue plate by design reinforcing components attach to the plate.

    Therefore we set up a design space (green block). The objective is max mode 1 frequency of the whole model, and constraint is max 0.5 volume fraction of the design space.

     

    However as the second image shown:

    1. Mostly only the element on the edge of the design space are left, and it's easy to understand they WON'T help to increase the plate natural frequency at all;

    2. The mid elements circled in black are "floating", meaning they are not attached to the plate at all.

     

    Could anyone help to figure out what I may do wrong in the setup?

    Thank you,

    Peter

     

    image.png

    image.png

    Door_opt_Topo_Opt.hm


  4. Hi,

     

    I just downloaded the student version. I followed the instruction and copy and pasted the license file in the directory, but still it doesn't work. It gives me the following error:

     

    Altair License Manager: License error

    Feature: GlobalZoneAM
    Error Code: 9
    Error Description:
    [LOCAL] C:/Program Files/Altair/14.0-edu/security/altair_lic.dat - (Err: 9) Feature not found

    Feature: HyperMesh
    Error Code: 9
    Error Description:
    [LOCAL] C:/Program Files/Altair/14.0-edu/security/altair_lic.dat - (Err: 9) Feature not found

    License Path: C:/Program Files/Altair/14.0-edu/security/altair_lic.dat

     

    I saw other forums so i tried:

     

    a) changing the file name of license file

    b)checking the ethernet id ( using the software provided on altair website it says the id is "00000000000000E0" whereas it is "0000000000E0" in the license file.

    c) trying to delete and create a system variable.

     

    So far nothing has worked. Please help.


  5. We want to do topology optimization on the hinge component (red) and the rest parts remain the same. The upper and lower surface of the pin (blue) is constrained (6DOF) and there is a 20N upward force on the edge of the door (yellow)

    We want the vertical deflection of the loading point on the door be less than 7 mm

    For now, we set the design constraint as the volume fraction value of the hinge, say 0.4 as the upper bound, and the objective is to minimize the compliance of the hinge.

     

    There are two questions:

    1. After the topo opt, the linking area between the hinge and the door is really weak, as Figure 2 shown. Is it because that we only considered the compliance of the hinge and hypwework will not consider the linking problem between components? If we modify the design area a little bit (leave the linking area as undesigned space), can we solve this problem? Or there is other ways to deal with it?

    2. After we got the topo result, we ran a FEA test and it showed that the deflection of the loading point exceeds the limit. Can we define a deflection limit as the design constraint before we run the topo opt? If so, how can we do that? If not, what can we do to minimize the deflection? (maybe we set a wrong objective?)

     

    Thank you!

    3.png

    4.png


  6. After so many problem posted on the forum, I finally see the result (plot iso of the last iteration) and it looks like Fig1:

     
    But after I use OSSmooth and export it as a stp file, I tried to re-import it, want to see what the new model looks like. But after I re-mesh the hinge, why it has those curves while the hinge body still remains intact (Fig 2)? I know those curves show the edge of the removed elements in Fig1, but I want a solid model that has a hole, not an intact model with edges of a hole. I've made the hinge component current so that's not the problem.
     
    What should I do to get a solid model that have elements removed from the topology optimization? 

    1.png

    2.png


  7. As suggested, I clicked the result button on solver window and now can view the topo result, but why I can see nothing changed on my design area (hinge)? It remain intact after topo opt? That makes no sense...

    And the slider below current value that change the density threshold ranges from 0 to 0, anything goes wrong?

     

    How can I see that which part of elements is removed from the original model?

    2.png


  8. 1 hour ago, Q.Nguyen-Dai said:

    Here're my remarks:

    1. Because it's the same material, you can merge two solids in order to avoir bad elements
    2. Because it's not the same material and because of tangential surface, there're ALWAYS some bad elements at this zone. You can decrease element size but that does not remove all bad elements.

    solid_hinge.png

    Yes, the blue comp (pin) and the red comp (hinge) are the same mat, but we only wanna do topology optimization on the hinge. I think that if we merge these two components, we'll unable to do optimization separately on the hinge, am I correct?

     

    For the second tip, now that bad elements always exist, does this mean we can never carry out the topo opt since we'll always fail the element quality check? How can we solve this problem? Skip the quality check, change the model geometry, or other ways?

     

    Thank you!

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